Macromolecules

As food travels through the digestive system, it is exposed to a variety of pH levels. The stomach has a pH of 2 due to the presence of hydrochloride acid (HCl), and the small intestine has a pH ranging from 7 to 9. HCl converts pepsinogen into pepsin, an enzyme that digests proteins in the stomach. Which of the following most likely happens to pepsin as it enters the small intestine?

• It becomes inactive.

• It begins to replicate.

• It's shape changes to engulf large proteins.

• It's activity increases to digest more proteins.

In living cells, enzymes act as catalysts, which may reduce the amount of activation energy required for a chemical reaction to occur. In the graphs below, pathway x is a solid line representing the uncatalyzed reaction. The dotted line shows the catalyzed reaction. Which graph best illustrates the changes in a reaction when the catalyst reduces the amount of energy required?

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The diagram below shows the general structure of an amino acid. Which type of molecule is formed from amino acids?

• lipids

• proteins

• carbohydrates

• nucleic acids

You are analyzing a compound in the laboratory. You find that it is made up of carbon, hydrogen, and oxygen in a ratio of two hydrogen atoms for each carbon atom. How will you classify the compound?

• lipid

• protein

• carbohydrate

• nucleic acid

RNA and DNA are which type of macromolecules?

• Carbohydrate

• lipid

• nucleic acid

• protein

What will most likely happen if an appropriate enzyme is added to a chemical reaction?

• The reaction rate will increase.

• The equilibrium of the reaction will be maintained.

• The reaction rate will decrease.

• The reaction will stop.

A sugar, a phosphate group, and a nitrogen base form the building blocks of which organic compound?

• carbohydrates

• lipids

• nucleic acids

• proteins

The human body maintains a temperature of around 98.6 degrees at all times. Enzymes are involved in almost every chemical reaction in the body. Which of the following describes the connection between these two statements?

• Enzymes function best at a specific temperature.

• The body needs to be warm to prevent hypothermia.

• The body is kept relatively warm to prevent too much enzyme action.

• There is no connection between the two statements.

Identify the biomolecule

• Carbohydrate
• Lipid
• Protein
• Nucleic Acid

Identify the macromolecule

• Lipid

• Protein

• Carbohydrate

• Nucleic Acid